It's yer thang! Just kidding! Respect his sincere intentions but make it clear that even if you would attend church it is b/c you love him & not b/c you think his position has merit.
I empathize with your position b/c it can be an emotional manipulation.

I never told my parents I was Atheist but I think they knew. I didn't want to hurt their feelings. Now that they are gone I wish I had been truthful with them.

Just say that you don't want to go to church because it isn't your thing. I wouldn't bother to go into much detail even if he asks because there's no purpose. Let him have his belief and you enjoy your non belief.